This thesis aims to restore the balance of modern investigations into Christian asceticism and anthropology by reading the texts of Sts. Irenaeus and Clement within their theological perspectives, and thereby examine the presuppositions determining how we think about sexual difference. In the Introduction I examine the projects of M. Foucault and P. Brown, arguing that they do not remain faithful to the concerns of the texts which they treat. In Part One, I show how asceticism, for Irenaeus, is the expression of the human living the life of God in the body, that which is most characteristically human and the image of God. Sexuality is fundamental to human existence, forming a permanent part of the framework within which humans grow towards God. This growth results from humans acting responsively to the creative activity of God. That God is the source of the life which is lived by humans, demands an openness on their part towards God. Any attempt to avoid the reality of their created nature, for instance, through a self-imposed continence, overturns the basic structure of this relationship. In Part Two, I consider the asceticism proposed by Clement, which strives, through human effort, to achieve a godlike life, buttressing the rational mind, that which is properly human and in the image of God, by the exercise of virtues, so protecting it from disturbances, especially those arising from the body and the vulnerability of dependency. Whilst Clement has a vivid sense of the new life granted in baptism, and praises marriage, this desire for a divine life leads inexorably to the restriction of human sexuality to the function of procreation and its redundancy thereafter. After summarizing, I indicate possible lines for further investigation, and suggest that only within the Irenaean perspective can the issue of sexual difference be raised meaningfully.